# Reverse engineering RMI

#### SJP07

##### Member
Hello!

The thinkorswim platform has a reverse engineering RSI and MACD indicator and I was wondering if someone could create a reverse engineering relative momentum index indicator for the upper chart. Below is the thinkorswim RMI code. Thanks in advance!

declare lower;
input length = 20;
input momentum = 5;

Assert(momentum > 0, "'momentum' must be positive: " + momentum);

def emaInc = ExpAverage(Max(close - close[momentum], 0), length);
def emaDec = ExpAverage(Max(close[momentum] - close, 0), length);
plot RMI = if emaDec == 0 then 0 else 100 - 100 / (1 + emaInc / emaDec);
plot OverBought = 70;
plot OverSold = 30;

Solution
Reverse Relative Momentum Index (RMI)

per member: @SJP07's request:
Ruby:
``````declare lower;
input length = 19;

def alpha = 2 / (length + 1);
def coeff = 1 - alpha;
def rmi = reference RelativeMomentumIndex() ;

def re1 = coeff * rmi + rmi[1];
def re2 = Power(coeff, 2) * re1 + re1[1];
def re3 = Power(coeff, 4) * re2 + re2[1];
def re4 = Power(coeff, 8) * re3 + re3[1];
def re5 = Power(coeff, 16) * re4 + re4[1];
def re6 = Power(coeff, 32) * re5 + re5[1];
def re7 = Power(coeff, 64) * re6 + re6[1];
def re8 = Power(coeff, 128) * re7 + re7[1];

plot ReverseRMI = rmi - alpha * re8;
plot ZeroLine = 0;
plot OverBought = 70;
plot OverSold = 30;

ReverseRMI.SetDefaultColor(GetColor(5));
ZeroLine.SetDefaultColor(GetColor(7));``````
Reverse Relative Momentum Index (RMI)

per member: @SJP07's request:
Ruby:
``````declare lower;
input length = 19;

def alpha = 2 / (length + 1);
def coeff = 1 - alpha;
def rmi = reference RelativeMomentumIndex() ;

def re1 = coeff * rmi + rmi[1];
def re2 = Power(coeff, 2) * re1 + re1[1];
def re3 = Power(coeff, 4) * re2 + re2[1];
def re4 = Power(coeff, 8) * re3 + re3[1];
def re5 = Power(coeff, 16) * re4 + re4[1];
def re6 = Power(coeff, 32) * re5 + re5[1];
def re7 = Power(coeff, 64) * re6 + re6[1];
def re8 = Power(coeff, 128) * re7 + re7[1];

plot ReverseRMI = rmi - alpha * re8;
plot ZeroLine = 0;
plot OverBought = 70;
plot OverSold = 30;

ReverseRMI.SetDefaultColor(GetColor(5));
ZeroLine.SetDefaultColor(GetColor(7));``````

Reverse Relative Momentum Index (RMI)

per member: @SJP07's request:
Ruby:
``````declare lower;
input length = 19;

def alpha = 2 / (length + 1);
def coeff = 1 - alpha;
def rmi = reference RelativeMomentumIndex() ;

def re1 = coeff * rmi + rmi[1];
def re2 = Power(coeff, 2) * re1 + re1[1];
def re3 = Power(coeff, 4) * re2 + re2[1];
def re4 = Power(coeff, 8) * re3 + re3[1];
def re5 = Power(coeff, 16) * re4 + re4[1];
def re6 = Power(coeff, 32) * re5 + re5[1];
def re7 = Power(coeff, 64) * re6 + re6[1];
def re8 = Power(coeff, 128) * re7 + re7[1];

plot ReverseRMI = rmi - alpha * re8;
plot ZeroLine = 0;
plot OverBought = 70;
plot OverSold = 30;

ReverseRMI.SetDefaultColor(GetColor(5));
ZeroLine.SetDefaultColor(GetColor(7));``````
Thanks!!! I appreciate the work you've done.

I notice that this is a lower study script. I was looking for something that's more like this, but for RMI:

#
# TD Ameritrade IP Company, Inc. (c) 2009-2021
#

input length = 14;
input price = close;
input rsiValue = 50.0;
input smoothingType = {default Wilders, EMA};

def coeff = rsiValue / (100 - rsiValue);
def chg = price - price[1];
def diff;
switch (smoothingType) {
case Wilders:
diff = (length - 1) * (WildersAverage(Max(-chg, 0), length) * coeff - WildersAverage(Max(chg, 0), length));
case EMA:
diff = (length - 1) * (ExpAverage(Max(-chg, 0), length) * coeff - ExpAverage(Max(chg, 0), length)) / 2;
}

def value = price + if diff >= 0 then diff else diff / coeff;
plot RevEngRSI = compoundValue(1, value[1], Double.NaN);

RevEngRSI.SetDefaultColor(GetColor(8));

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